Seagate ST3285N, Product Manual

Page: 30 / 151

2.7 DC power connector
The drive is equipped with a 4-pin power connector as shown in Figure 7
on page 25.
2.8 Terminators
The interface is terminated with three SIP resistor modules that plug into
sockets on the printed circuit board. You can order the drive in the active
(default) or passive configuration, or without terminators, depending on
your application. For terminator jumper configurations, see Section 2.9.
When installing or removing terminators, follow these guidelines:
•
If you are installing only one drive, and your system contains only one
initiator (for example, a stand-alone host computer) leave the termi-
nators installed on the drive.
•
If you are installing multiple drives in a daisy-chain configuration,
remove the terminators from all drives except the drives (or initiators)
connected to the ends of the cable.
•
If your application requires no terminators, remove the terminators
from the drive circuit board. Removing the terminator power source
selection jumper does not disconnect the terminator resistors from the
circuit.
•
If you use Fast SCSI transfer rates, you must use the active termina-
tion options. See Sections 2.8.1 and 2.9.5. If the transfer rate is
5.0 Mbytes per second or less, you can use either method of termina-
tion.
2.8.1 Active termination
All interface signals are single-ended and must be terminated at the drive
with a 110-ohm resistor to +2.85V. This is the default. The Seagate
® part
number for the 110-ohm terminator is 502155-001.
20 ST3655 Family SCSI Drives Product Manual, Rev. A